The present invention is related to liquid dispensing systems. In particular, the present invention relates to pumping mechanisms for paint sprayers.
Sprayers are well known and popular for use in painting of surfaces, such as on architectural structures, furniture and the like. Airless paint sprayers provide the highest quality finish amongst common sprayer systems due to their ability to finely atomize liquid paint. In particular, airless paint sprayers pressurize liquid paint to upwards of 3,000 psi [pounds per square inch] (˜20.7 MPa) and discharge the paint through small, shaped orifices. Typical airless sprayer systems, however, require a large stationary power unit, such as an electric motor, a gasoline motor or an air compressor, and a large stationary pumping unit to generate such large pressures. The power unit is connected to a stationary paint source, such as a 5 gallon (˜18.9 liter) bucket, and a spray gun. These stand units, as they are commonly referred to, are expensive due to heavy duty construction, numerous components and manufacturing costs, but are well suited for painting large areas that require high quality finishes.
It is also desirable to paint smaller areas for which it is not desirable or feasible to set up a stationary stand unit system. For example, it is desirable to provide touch-up and trim areas having finishes that match areas originally painted with a stand unit. Various types of handheld sprayer systems and units have been developed to address such situations. For example, buzz guns or cup guns, as they are commonly referred to, comprise small handheld devices electrically powered by connection to a power outlet. For example, some handheld units use piston pumps that are actuated using crank and rod assemblies or bevel gear assemblies, as described in U.S. Pat. No. 2,488,789 to Williams and U.S. Pat. No. 2,629,539 to Drewes, Jr., respectively. These pumping mechanisms, however, have many intricate parts that increase the cost and size of manufacturing handheld units beyond feasibility.
There is, therefore, a need for a pumping mechanism that, among other things, reduces the expense of manufacturing airless sprayers.